Maryam Nawaz Sharif, a leading figure in Pakistan’s political opposition, has been arrested by anti-graft authorities.
She was visiting her father, the jailed former Prime Minister Nawaz Sharif, when she was taken into custody.
The country’s National Accountability Bureau (NAB) said she was being held in connection with a money laundering investigation.
Her PML-N party said the arrest was politically motivated.
Ms Nawaz’s cousin, Yousaf Abbas Sharif, was also arrested. The pair will appear before a Lahore court on Friday.
In a brief statement the NAB, an anti-corruption watchdog, said that Ms Nawaz was detained in connection with a corruption investigation involving a sugar mill owned by the Sharif family.
Ms Nawaz has led several large political rallies in recent weeks and is a vocal critic of Prime Minster Imran Khan and Pakistan’s powerful military.
Parts of her speeches at these rallies have been muted during television broadcasts within Pakistan, but Mr Khan and the military have denied accusations of censorship.
The Sharif family has dominated Pakistani politics for decades and has been embroiled in several high-profile corruption cases.
The family says the cases are motivated by political grudges.
Nawaz Sharif, a three-time prime minister, is serving a seven-year sentence for corruption. He was disqualified from office in July 2017 and his brother, Shahbaz Sharif, was the PML-N’s candidate in last year’s elections won by Imran Khan’s PTI party.
Ms Nawaz herself was released on bail last year after her own corruption sentence was suspended.